Until now, a technique has been proposed which allows a signal line serving as a medium of transmission and reception of signals between an indoor unit and an outdoor unit of an air conditioner to additionally serve as a function of power supply (power feeding) under a certain circumstance. Hereinafter, this will be briefly introduced.
For example, when a cooling and heating function of an indoor unit is not necessary and only an air-blowing function is required to function, a refrigerant cycle operation of an outdoor unit is not necessary. For such a case, one proposal has been made that the driving of a compressor of the outdoor unit is stopped to make the outdoor unit transition into a so-called operation-standby mode so that the power consumption is reduced. In this case, a path for feeding power to the compressor, and a path for feeding power to a control device which controls the driving of the compressor are interrupted. However, the power supply path of the control device which controls the driving of the compressor is connected to a signal line.
For the return from the operation-standby mode to a normal operation, electric power is fed to the signal line in the indoor unit side and a driving power is supplied to the control device. Thereby, the above power feeding path is connected to the compressor to drive. Such a technique is introduced, for example, in Japanese Patent Publication No. 4547950 described below.
On the other hand, an air conditioner in which a single outdoor unit is connected to a plurality of indoor units (hereinafter referred to as “a multi-indoor unit type air conditioner”) has also been proposed until now. The multi-indoor unit type air conditioner is provided with a plurality of signal lines, corresponding to the indoor units. The outdoor unit includes transmission/reception units to each of signal lines, and performs transmission and reception of signals for each of indoor units. Such a technique is introduced, for example, in Japanese Patent Application Laid-Open No. 63-306346 (1988) described below.